Re: [PATCH] target/riscv: Remove experimental prefix from "B" extension

[Andrew Jones]

On Thu, May 09, 2024 at 02:23:42PM GMT, Daniel Henrique Barboza wrote:
> 
> 
> On 5/8/24 08:22, Andrew Jones wrote:
> > On Tue, May 07, 2024 at 11:27:21AM GMT, Rob Bradford wrote:
> > > This extension has now been ratified:
> > > https://jira.riscv.org/browse/RVS-2006 so the "x-" prefix can be
> > > removed.
> > > 
> > > Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
> > > ---
> > >   target/riscv/cpu.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> > > index eb1a2e7d6d..861d9f4350 100644
> > > --- a/target/riscv/cpu.c
> > > +++ b/target/riscv/cpu.c
> > > @@ -1396,7 +1396,7 @@ static const MISAExtInfo misa_ext_info_arr[] = {
> > >       MISA_EXT_INFO(RVJ, "x-j", "Dynamic translated languages"),
> > >       MISA_EXT_INFO(RVV, "v", "Vector operations"),
> > >       MISA_EXT_INFO(RVG, "g", "General purpose (IMAFD_Zicsr_Zifencei)"),
> > > -    MISA_EXT_INFO(RVB, "x-b", "Bit manipulation (Zba_Zbb_Zbs)")
> > > +    MISA_EXT_INFO(RVB, "b", "Bit manipulation (Zba_Zbb_Zbs)")
> > >   };
> > >   static void riscv_cpu_validate_misa_mxl(RISCVCPUClass *mcc)
> > > -- 
> > > 2.44.0
> > > 
> > > 
> > 
> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> > 
> > I think we should also either change the false to true for RVB in
> > misa_ext_cfgs[] or at least ensure RVB is set for the 'max' cpu
> > type in riscv_init_max_cpu_extensions().
> 
> I prefer if we keep misa_ext_cfgs[] as is. Changing the defaults in this array
> will also change the defaults for rv64. IMO we should enable RVB manually in
> riscv_init_max_cpu_extensions().
> 
> We already have some precedence for it: RVV is enabled in 'max' while is 
> default
> 'false' for rv64.

But do we care if rv64 gets B? rv64 doesn't have any particular set of
extensions, afaik. And B seems like it should be generally adopted enough
to be in a "general" cpu type like rv64. Anyway, either way works for me
as long as 'max' gets B one way or another.

Thanks,
drew